1. Field of the Invention
The present invention relates to a yarn winding apparatus, more particularly, to a yarn winding apparatus which enables one to wind yarn at a high speed on a long spindle having a small diameter while avoiding serious spindle vibration.
2. Description of the Related Art
Recent yarn winding apparatuses have been increased in the speed of the spindles with, for example, take yarn up at more than 5000 m/min, to improve the productivity of the yarn making process.
Also, use has been made of a spindle carrying multiple bobbins. In other words, a spindle having a relatively longer length, to further improve the productivity, since a plurality of yarn packages can be obtained in one winding operation.
A yarn winding apparatus having a longer spindle capable of carrying multiple bobbins is already known from EP 234,844, for example.
When spindles carrying multiple bobbins are put into practical use, the amount of the bobbins consumed will be increased remarkably since a large number of bobbins are mounted on the spindles in one yarn winding operation.
At the present time, bobbins are not collected for reuse but are scrapped after one use.
This is because great expense is required to manage and collect the bobbins both in term of equipment and personal.
Generally, the dominant expense in the production of bobbins is the material cost.
Bobbins having a relatively small diameter are thus naturally cheaper than bobbins having a relatively large diameter.
Also, when the diameter is reduced, the volume of yarn wound on a bobbin in one winding operation is increased, contributing to larger sized package.
Also, when the diameter is reduced, the volume of yarn wound on a bobbin having a small diameter, in other words, a spindle having a small diameter, and to increase the speed of the spindle for winding yarn and to elongate the spindles in a yarn winding apparatus.
In the prior art, there has not been a practical yarn winding apparatus which features simultaneously an increased rotational speed of the spindles, a greater spindle length, and a minimized spindle diameter.
Note that, conventional yarn winding apparatuses feature a maximum yarn winding speed of 6000 m/min, spindles made of metal and having a inner diameter of 120 mm and a total length of bobbins mounted on the spindles of 1200 mm.
Rotating bodies made of a composite layer made of reinforcing fibers and a matrix component are sometimes seen in the field of centrifugal separators.
A spindle of such a composite layer made of reinforcing fibers and a matrix component is very inferior to a spindle made of metal in mechanical strength, such as surface hardness, impact resistance, and wear and abrasion resistance. Therefore wear and deform action will occur on the sliding portion between a cylindrical body, i.e., a bobbin holder, and a bobbin fixing device, the connecting portion between the cylindrical body and a boss, the connecting portion between the boss and the driving shaft of the bobbin holder, and a bearing portion for supporting the driving shaft, due to frequent usuage of the yarn winding apparatus.
This wear and deform action cause considarable vibration, significantly reducing reliability and durability.
Therefore, spindles made of composite layer made of reinforcing fibers and a matrix component have not been used in practice.
On the other hand, a high speed rotating cylindrical body made of a composite layer made of reinforcing fibers and a matrix component and used for yarn winding apparatus is known in Japanese Unexamined Patent Publication No. 56-147916.
However, in the prior art, there is no information about the usage of a long spindle carrying multiple bobbins having a relatively small diameter for high speed yarn winding.
When a spindle made of a composite layer made of reinforcing fibers and a matrix component is used in a yarn winding apparatus, the precision of processing, the surface hardness, and the like of the sliding portion, the connecting portions, and the bearing portion are required to be high to enable high speed spindle performance.
In addition, this high level of precision should be maintained at a constant level without any variation with time caused by vibration due to rotation of the spindle, variation in package weight, or external force or stress, for example, the binding force created on the connecting portion.
When a yarn winding apparatus enabling high speed yarn winding with a long spindle made of metal having a small diameter is used, the increased spindle length naturally causes less stiffness of the spindle and a weaker supporting construction.
A separate problem arises in that other vibration will occur due to lack of spindle strenth, thus hindering high speed yarn winding.
Generally, it is believed that high speed yarn winding at a stable condition, requires that the spindle rotated at a high speed, be used without approaching the critical speed causing a considerable bending vibration, from the start to the end of yarn winding.
When high speed yarn winding is carried out utilizing a long spindle made of metal having a smaller diameter, for example, having an inner diameter of 94 mm and the whole length of 1200 mm, the critical speed is generally around 6000 m/min.
In other words, the critical speed drops to an unprecedantedly low range of yarn winding speed in which no critical speed occurs heretofore.
If vibration occurs in yarn winding at a speed of around 6000 m/min, it is difficult to continue stable yarn winding and furher there is mechanical damages to the yarn winding apparatus.
Thus, this kind of yarn winding apparatus cannot be used in practice.